Assessment of the Urban Water Cycle in Antwerp (BE): The City Blueprint Approach (CBA)

Abstract The City Blueprint Approach (CBA) is applied to assess the urban water cycle and sustainability in Antwerp, Belgium. Using two complementary frameworks. The Trends and Pressures Framework (TPF) assesses the city’s main social, environmental, financial and governmental challenges based on 18 indicators. The City Blueprint (performance) Framework (CBF) deals with the adequacy of the city’s water management, based on 24 mostly-quantitative indicators. The Blue City Index is the geometric mean of the performance-based indicators in the CBF. Our analysis of the TPF identified five major indicators reflecting concern for the urban water cycle of Antwerp: Water Scarcity, Flood Risk, Water Quality, Air Quality (all environmental concerns) and the Unemployment Rate. Antwerp experiences periodic flooding accentuated by sea level rise. Water abstraction rates compared to available water resources reflects water scarcity of ∼ 33 %.. The fraction of surface water bodies not achieving ‘good’ ecological status exceeds 90% due to hydromorphological modifications, diminished ecological functioning, and chemical contaminants. Mean air quality in the city exceeds air quality standards several days per year. The CBF framework identifies 4 indicators reflecting ‘poor’ performance for the urban water cycle of Antwerp: GW quality, stormwater separation (CSOs), age of the sewer system and quantity of green space. Less than 25% of the groundwater bodies are of good chemical and/or quantitative status in the Scheldt river basin. The city currently has only limited stormwater separation sewers; separating CSOs is costly. The average age of the sewer system in Flanders is between 25 and 49 years, 66 years old in Antwerp. Sewers are replaced after ∼75 years of service, making water infrastructure a main area of concern. Antwerp’s green space (∼17%) is being expanded promoting cooling in warm periods, improves social cohesion and well-being of citizens, and reduces the risk of urban flooding. Having a Blue City Index of 6.2/10, Antwerp ranks amongst the top 20 cities performances (>70 cities). The CBA identifies pressures acting upon the city and its performance on water sustainability in Antwerp. Analyzing the CBF creates opportunities in enhancing water sustainable development.